THAI authorities today charged 30 Britons and ten Irishmen suspected of being part of an illegal investment scam that defrauded foreign investors of more than #100 million.

Most were accused of working illegally in Thailand but Kealy John Martin, from Ireland, and an Australian were charged with setting up illegal securities companies.

The charges were presented in a Bangkok court which accepted the cases allowing police to detain the suspects pending an investigation into the more serious crime of committing financial fraud.

Bangkok police arrested more than 100 people yesterday in raids on two stock trading "boiler rooms" following complaints by foreign investors - mainly from Australia, Hong Kong and New Zealand - that they had been cheated out of their money.

A total of 85 foreigners and 17 Thais were arrested at the offices of the Brinton Group and Benson Dupont Capital Management, two companies accused by securities regulators of running unlicensed securities services and defrauding foreign investors.

The firms, at Bangkok City Tower and Sethiwan Tower in central Bangkok, could be the headquarters for a securities scheme spanning 70 countries.

The FBI and Australian police took part in the raids.

Prasarn Trairatvorakul, secretary-general of Thailand's Securities Exchange Commission, said the case emerged after complaints from securities regulators in Australia, New Zealand and Hong Kong about investors receiving "cold calls" from people in Thailand to invest in stock.

"It's very difficult to follow these groups, which move very quickly and conceal their operations by renting 'virtual' offices to act as a switchboard," Dr Prasarn said.

"The calls are then routed to other locations where they maintain a physical presence.

"More than 100 Australian investors were allegedly contacted. The offices had more than 60 telephone lines put in, with phone records showing frequent calls made overseas. Other evidence included brochures advertising the businesses as securities brokers and investment managers.

One Australian among the foreigners arrested said he had worked with the group for several months.

"I didn't really know what they were doing," the 30-year-old said. "The company hired me as a telephone operator to contact investors and said they'd pay me. So I thought, why not?"

The SEC warned that another 21 companies running in Thailand had been named in complaints by foreign investors and were potentially running unlicensed securities services.

"Today's case is an example. We want to caution investors, Thais and foreigners, to exercise care before making any commitments," Dr Prasarn said.

"We do not want to see Thailand viewed as a centre of international crimes such as this."

Prime Minister Thaksin Shinawatra promised a review of visas for foreign workers, and pointed to weaknesses in immigration screening, and lax blacklisting system.